/***************************************************************************
 *   Copyright (c) 2004 Werner Mayer <wmayer[at]users.sourceforge.net>     *
 *                                                                         *
 *   This file is part of the FreeCAD CAx development system.              *
 *                                                                         *
 *   This library is free software; you can redistribute it and/or         *
 *   modify it under the terms of the GNU Library General Public           *
 *   License as published by the Free Software Foundation; either          *
 *   version 2 of the License, or (at your option) any later version.      *
 *                                                                         *
 *   This library  is distributed in the hope that it will be useful,      *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU Library General Public License for more details.                  *
 *                                                                         *
 *   You should have received a copy of the GNU Library General Public     *
 *   License along with this library; see the file COPYING.LIB. If not,    *
 *   write to the Free Software Foundation, Inc., 59 Temple Place,         *
 *   Suite 330, Boston, MA  02111-1307, USA                                *
 *                                                                         *
 ***************************************************************************/


#ifndef GUI_PROGRESSBAR_H
#define GUI_PROGRESSBAR_H

#include <QProgressBar>

#include <Base/Sequencer.h>

namespace Gui {

struct SequencerPrivate;
struct ProgressBarPrivate;
class ProgressBar;

/**
 * FreeCAD's progress bar for long operations
 * To see how to use the progress bar have a look at the following examples:
 *
 * \code
 * unsigned long steps = ...
 * Base::SequencerLauncher seq("Starting progress bar", 0);
 *
 * for (unsigned long i=0; i<steps;i++)
 * {
 *   seq.next();
 *   // do one step of your algorithm
 * }
 * 
 * \endcode
 *
 * The example below shows how to use two nested progresses.
 *
 * \code
 * void function1()
 * {
 *   unsigned long steps = ...
 *   Base::SequencerLauncger seq("Starting progress bar", 0);
 *
 *   for (unsigned long i=0; i<steps;i++)
 *   {
 *     seq.next();
 *     // do one step of your algorithm
 *   }
 *
 * }
 * 
 * void function2()
 * {
 *   unsigned long steps = ...
 *   Base::SequencerLauncher seq("Starting progress bar", 0);
 *
 *   for (unsigned long i=0; i<steps;i++)
 *   {
 *     seq.next();
 *     // do one step of your algorithm calling function1
 *     function1();
 *   }
 * }
 *
 * \endcode
 *
 * If the total number of steps cannot be determined before, use 0 instead of to show
 * just a busy indicator instead of percentage steps.
 * @author Werner Mayer
 */
class GuiExport Sequencer : public Base::SequencerBase
{
public:
    /** Returns the sequencer object. */
    static Sequencer* instance();
    /** This restores the last overridden cursor and release the keyboard while the progress bar 
    * is running. This is useful e.g. if a modal dialog appears while a long operation is performed
    * to indicate that the user can click on the dialog. Every pause() must eventually be followed 
    * by a corresponding @ref resume().
    */
    void pause();
    /** This sets the wait cursor again and grabs the keyboard. @see pause() */
    void resume();
    bool isBlocking() const;
    /** Returns an instance of the progress bar. It creates one if needed. */
    QProgressBar* getProgressBar(QWidget* parent=0);

protected:
    /** Construction */
    Sequencer ();
    /** Destruction */
    ~Sequencer ();

    /** Puts text to the status bar */
    void setText (const char* pszTxt);
    /** Starts the progress bar */
    void startStep();
    /** Increase the progress bar. */
    void nextStep(bool canAbort);
    /** Sets the progress indicator to a certain position. */
    void setProgress(size_t);
    /** Resets the sequencer */
    void resetData();
    void showRemainingTime();

private:
    /** @name for internal use only */
    //@{
    void setValue(int step);
    /** Throws an exception to stop the pending operation. */
    void abort();
    //@}
    SequencerPrivate* d;
    static Sequencer* _pclSingleton;

    friend class ProgressBar;
};

class ProgressBar : public QProgressBar
{
    Q_OBJECT

public:
    /** Construction */
    ProgressBar (Sequencer* s, QWidget * parent=0);
    /** Destruction */
    ~ProgressBar ();

    /** Handles all incoming events while the progress bar is running. All key and mouse
    * events are ignored to block user input.
    */
    bool eventFilter(QObject* o, QEvent* e);
    /** Returns the time in milliseconds that must pass before the progress bar appears.
    */
    int minimumDuration() const;

public Q_SLOTS:
    /** Sets the time that must pass before the progress bar appears to \a ms.
    */
    void setMinimumDuration (int ms);

    bool canAbort() const;

protected:
    void showEvent(QShowEvent*);
    void hideEvent(QHideEvent*);

protected Q_SLOTS:
    /* Shows the progress bar if it is still hidden after the operation has been started
    * and minimumDuration milliseconds have passed.
    */
    void delayedShow();
    void aboutToShow();

private:
    /** @name for internal use only */
    //@{
    void resetObserveEventFilter();
    /** Gets the events under control */
    void enterControlEvents();
    /** Looses the control over incoming events*/
    void leaveControlEvents();
    //@}
    ProgressBarPrivate* d;
    Sequencer* sequencer;

    friend class Sequencer;
};

} // namespace Gui

#endif // GUI_PROGRESSBAR_H